Engine/Transmission (1998.5 - 2002) Rear diff service

[Tractorat]

I just had the service done to my rear differential. The guy swore up and down that they dont need to add friction modifier to the synthetic stuff. Im not sure that I believe him. can someone enlighten me ?



Thanks,

TRat

 

[Ram4Sam]

I don't know about Amzoil and others but Royal Purple does not need any added, it already has it.



Sam

 

[HBarlow]

Gen III differentials are of a different design than the old Danas and do not require a friction modifier. All they require is the specified synthetic gear lube.

 

[WStephens]

The AA rear has a gear type locking device and the Dana axles had clutch packs that needed the friction modifier.

 

[kenny61]

many different brands of gear oil have the limited slip additive already added

 

[Curious Dave]

I believe you need to reed the bottles instructions. It should say something on it about compatibility with clutch type differentials. It may use the word posi or something else that relates to the type of carrier.

 

[BDaugherty]

If your 02 has a limited slip rear diff, the factory manual calls for friction modifier. However, some oil manufacturers say it's not needed due to additives they use. Amsoil says not to add modifier unless you experience chatter. In my experience, if you have a lot of miles on a factory limited slip that has not been rebuilt or restacked, you will not need modifier regardless of oil used.

If I were in your shoes, I would let it ride. If you start to have chatter, add a bottle of the modifier.

I don't agree with the premis of this arguement, but a lot of guys that I know leave out the modifier on purpose in order to make the limited slip grab harder.

 

[DIESELWRKS]

I just had the service done to my rear differential. The guy swore up and down that they dont need to add friction modifier to the synthetic stuff. Im not sure that I believe him. can someone enlighten me ?



Thanks,

TRat

on your Dana. use a synthetic GL-5 rated. like royal purple or redline. they both have limited slip added in them. i have used both for many miles and never a problem. usually redline is a little cheaper than royal purple. and both are alot cheaper than the stuff you get at the stealership..... just my 2 cents. when you do your change if you have never done it. remove the cover clean it up really good. scoop out all that you can. do a visual inspect of the ring, etc. clean the gasket surface area. you can order a gasket for your cover or use RTV. I have a aftermarket cover so mine has a reusable gasket. dont spray any type of cleaner in the gears/ring area you dont need to do this. you can however buy a bigger magnet. and place it on your cover and this will give you a little extra protection for small particles to collect. just my 2 cents. good luck. oh and use some blue locktite on the bolts.

 

[SnoKing]

Go into a parking lot and do figure 8's. If you feel the LSD chattering add I half bottle of additive and drive it a bit and repeat the figure 8's, repeat adding and testing until the chattering stops. You most likely are CAD-less, so don't confuse front axle hop in tight turns, which you might have a little bit of without the CAD, with LSD clutch chattering in the rear. SNOKING

 

[Batphreak]

Snoking has the way to figure it out right, there. I can speak a little for 2 brands. My old Dakota had a Corp 9. 5" rearend, I put AMSOIL in it and had NO chatter problems. A month or so ago I put Lucas Synthetic lube in the current truck and the clutch pack is chattering all over the place on me, I'm going to have to put some modifier in there, just haven't gotten to it yet.